Converting An Onan Twin To A Single Output Coil

my 1975 SS 16 has a bad ignition coil, and i am working on the idea of using one of many single output coils i have on hand. The issue i have is how to effectivly insulate the junction of the spark plug wires into one lead that can be inserted into the high voltage tower on the coil. previous attempts have shown that standard electrican's tape is not up to the task.(at least in my attempts) Any outher thoughts on how to effectivly insulate this junction will be appricated.....DrBob762.

Silicon Glue with thick wall heat shrink should work... But I'm afraid you will have intermittent problems.
Electricity will take the path of least resistance, the cylinder NOT under compression would have less resistance at the plug, so the spark will possibly go there instead of the cylinder that should fire. It might work once in a while, but changes in humidity, heat, mix, etc could cause it not to work right or not be consistent.

You would be better off to do two small coils IMHO. I have thought the same about motorcycle coils or something. Someone said that a dual output Harley coil will work, might look into that. They would be two coils in one case, not one coil split.